http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50568 --- Comment #17 from H.J. Lu <hjl.tools at gmail dot com> 2011-09-29 18:34:38 UTC --- Also I don't believe it is 100% safe to use %x for printf/scanf on 64bit integer even on 64bit hosts. I think 64bit random seed change should be reverted for now.